File Download
Supplementary

postgraduate thesis: Polyamide membranes enhanced by interfacial nanostructures : towards high performance thin-film composite membrane fabrication for water purification

TitlePolyamide membranes enhanced by interfacial nanostructures : towards high performance thin-film composite membrane fabrication for water purification
Authors
Advisors
Advisor(s):Tang, C
Issue Date2018
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Yang, Z. [杨哲]. (2018). Polyamide membranes enhanced by interfacial nanostructures : towards high performance thin-film composite membrane fabrication for water purification. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.
AbstractWater crisis is one of the most serious problems in this new millennium. Membrane technology can potentially address this issue via seawater desalination or wastewater reclamation. However, the state-of-the-art thin-film composite membrane (TFC), which is the dominated material of the desalination membranes, still has limited desalination efficiency and high energy costs due to its unsatisfactory separation performance, such as relatively low water permeability and salt selectivity. The thesis aims to fabricate a series of novel nanostructure enhanced TFC membranes to improve membrane water permeability and salt rejection. The resulting membranes successfully overcame the permeability-selectivity correlation upper bound of the conventional TFC membranes. We first coated a polydopamine (PDA) layer on a polysulfone substrate, followed by immersing it in AgNO3 solution to in situ generate uniformly distributed silver nanoparticles (AgNPs). Followed by interfacial polymerization reaction between piperazine (PIP) and trimesoyl chloride (TMC), a polyamide rejection layer was fabricated on the polysulfone substrate with PDA/Ag nanostructure. The resulting membrane showed enhanced water permeability, salt rejection and antimicrobial compared to those of the control TFC and conventional TFN membranes thanks to the uniformly generated AgNPs inside PDA layer. Furthermore, a green and facile nanostructure using the complex of the coordination between tannic acid (TA) and ferric ions (Fe3+) was introduced to the substrate, followed by interfacial polymerization to fabricate the ultimate TFC membrane. The TFC membrane with TA-Fe nanostructure showed a water permeability of 19.6  0.5 Lm-2h-1bar-1, which was an order of magnitude higher than that of control TFC membrane (2.2  0.3 Lm-2 h-1 bar-1). At the same time, this novel membrane also had enhanced salt rejection. Membrane characterizations using quartz crystal microbalance revealed the TA-Fe nanostructure could enhance the loading of PIP monomers and provided a platform for their controlled release. The TA-Fe coated substrate further eliminated the intrusion of polyamide into the substrate pores, which played a vital role in enhancing the membrane water permeability. Copper nanoparticles (CuNPs) nanostructure was first on the polysulfone substrate, followed by the interfacial polymerization reaction between m-phenylenediamine (MPD) and TMC. The CuNPs contained in the TFC membrane were then etched by HCl to generate nanovoids inside the polyamide rejection layer. These nanovoids further rendered the HCl etched TFC membrane shortcuts for faster water transport with only slightly reduced salt rejection. PDA nanostructure was further applied on a hydrolyzed polyacrylonitrile (PAN) substrate, followed by interfacial polymerization reaction between polyethyleneimine (PEI) and TMC to obtain a positively charge nanofiltration membrane. The coating time of polydopamine layer was further investigated to fine-tune membrane water permeability and salt rejection. Furthermore, the nanofiltration membrane with PDA nanostructure had enhanced anti-swelling properties by alcohol treatment due to the bio-glue properties of PDA layer. Overall, this thesis investigates a series of nanostructure assisted TFC membranes with enhanced water permeability as well as salt rejection. It reveals the mechanistic insights of how the interlayers assisted the TFC membranes to achieve enhanced separation performance. These results offer a new avenue of fabricating next-generation TFC membranes with excellent separation performance for seawater desalination and wastewater reclamation.
DegreeDoctor of Philosophy
SubjectPolyamide membranes
Purification - Water
Dept/ProgramCivil Engineering
Persistent Identifierhttp://hdl.handle.net/10722/277096

 

DC FieldValueLanguage
dc.contributor.advisorTang, C-
dc.contributor.authorYang, Zhe-
dc.contributor.author杨哲-
dc.date.accessioned2019-09-19T02:44:30Z-
dc.date.available2019-09-19T02:44:30Z-
dc.date.issued2018-
dc.identifier.citationYang, Z. [杨哲]. (2018). Polyamide membranes enhanced by interfacial nanostructures : towards high performance thin-film composite membrane fabrication for water purification. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.-
dc.identifier.urihttp://hdl.handle.net/10722/277096-
dc.description.abstractWater crisis is one of the most serious problems in this new millennium. Membrane technology can potentially address this issue via seawater desalination or wastewater reclamation. However, the state-of-the-art thin-film composite membrane (TFC), which is the dominated material of the desalination membranes, still has limited desalination efficiency and high energy costs due to its unsatisfactory separation performance, such as relatively low water permeability and salt selectivity. The thesis aims to fabricate a series of novel nanostructure enhanced TFC membranes to improve membrane water permeability and salt rejection. The resulting membranes successfully overcame the permeability-selectivity correlation upper bound of the conventional TFC membranes. We first coated a polydopamine (PDA) layer on a polysulfone substrate, followed by immersing it in AgNO3 solution to in situ generate uniformly distributed silver nanoparticles (AgNPs). Followed by interfacial polymerization reaction between piperazine (PIP) and trimesoyl chloride (TMC), a polyamide rejection layer was fabricated on the polysulfone substrate with PDA/Ag nanostructure. The resulting membrane showed enhanced water permeability, salt rejection and antimicrobial compared to those of the control TFC and conventional TFN membranes thanks to the uniformly generated AgNPs inside PDA layer. Furthermore, a green and facile nanostructure using the complex of the coordination between tannic acid (TA) and ferric ions (Fe3+) was introduced to the substrate, followed by interfacial polymerization to fabricate the ultimate TFC membrane. The TFC membrane with TA-Fe nanostructure showed a water permeability of 19.6  0.5 Lm-2h-1bar-1, which was an order of magnitude higher than that of control TFC membrane (2.2  0.3 Lm-2 h-1 bar-1). At the same time, this novel membrane also had enhanced salt rejection. Membrane characterizations using quartz crystal microbalance revealed the TA-Fe nanostructure could enhance the loading of PIP monomers and provided a platform for their controlled release. The TA-Fe coated substrate further eliminated the intrusion of polyamide into the substrate pores, which played a vital role in enhancing the membrane water permeability. Copper nanoparticles (CuNPs) nanostructure was first on the polysulfone substrate, followed by the interfacial polymerization reaction between m-phenylenediamine (MPD) and TMC. The CuNPs contained in the TFC membrane were then etched by HCl to generate nanovoids inside the polyamide rejection layer. These nanovoids further rendered the HCl etched TFC membrane shortcuts for faster water transport with only slightly reduced salt rejection. PDA nanostructure was further applied on a hydrolyzed polyacrylonitrile (PAN) substrate, followed by interfacial polymerization reaction between polyethyleneimine (PEI) and TMC to obtain a positively charge nanofiltration membrane. The coating time of polydopamine layer was further investigated to fine-tune membrane water permeability and salt rejection. Furthermore, the nanofiltration membrane with PDA nanostructure had enhanced anti-swelling properties by alcohol treatment due to the bio-glue properties of PDA layer. Overall, this thesis investigates a series of nanostructure assisted TFC membranes with enhanced water permeability as well as salt rejection. It reveals the mechanistic insights of how the interlayers assisted the TFC membranes to achieve enhanced separation performance. These results offer a new avenue of fabricating next-generation TFC membranes with excellent separation performance for seawater desalination and wastewater reclamation. -
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.subject.lcshPolyamide membranes-
dc.subject.lcshPurification - Water-
dc.titlePolyamide membranes enhanced by interfacial nanostructures : towards high performance thin-film composite membrane fabrication for water purification-
dc.typePG_Thesis-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplineCivil Engineering-
dc.description.naturepublished_or_final_version-
dc.date.hkucongregation2018-
dc.identifier.mmsid991044058182003414-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats